DRV593

DRV594

SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002

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17

FIXED INTERNAL GAIN

The differential output voltage may be calculated using equation (10):

V

O +

V

OUT

)

–V

OUT– +

and minimum ratings are provided in the electrical specification table at the beginning of the data sheet.

POWER SUPPLY DECOUPLING

To reduce the effects of high-frequency transients or spikes, a small ceramic capacitor, typically 0.1

µF to 1 µF,

should be placed as close to each set of PVDD pins of the DRV593 and DRV594 as possible. For bulk

decoupling, a 10

µF to 100 µF tantalum or aluminum electrolytic capacitor should be placed relatively close to

the DRV593 and DRV594.

AREF CAPACITOR

The AREF terminal is the output of an internal mid-rail voltage regulator used for the onboard oscillator and ramp

generator. The regulator may not be used to provide power to any additional circuitry. A 1

µF ceramic capacitor

must be connected from AREF to AGND for stability (see oscillator components above for AGND connection

information).

SHUTDOWN OPERATION

The DRV593 and DRV594 include a shutdown mode that disables the outputs and places the device in a low

supply current state. The SHUTDOWN pin may be controlled with a TTL logic signal. When SHUTDOWN is

held high, the device operates normally. When SHUTDOWN is held low, the device is placed in shutdown. The

SHUTDOWN pin must not be left floating. If the shutdown feature is unused, the pin may be connected to VDD.

FAULT REPORTING

The DRV593 and DRV594 include circuitry to sense three faults:

These three fault conditions are decoded via the FAULT1 and FAULT0 terminals. Internally, these are

open-drain outputs, so an external pullup resistor of 5 k

Ω or greater is required.

Table 2. Fault Indicators

FAULT1

FAULT0

0

0

Overcurrent

1

0

Undervoltage

0

1

Overtemperature

1

1

Normal operation

The overcurrent fault is reported when the output current exceeds four amps. As soon as the condition is

sensed, the overcurrent fault is set and the outputs go into a high-impedance state for approximately 3

µs to

5

µs (500 kHz operation). After 3 µs to 5 µs, the outputs are re-enabled. If the overcurrent condition has ended,

the fault is cleared and the device resumes normal operation. If the overcurrent condition still exists, the above

sequence repeats.

The undervoltage fault is reported when the operating voltage is reduced below 2.8 V. This fault is not latched,

so as soon as the power supply recovers, the fault is cleared and normal operation resumes. During the

undervoltage condition, the outputs go into a high-impedance state to prevent overdissipation due to increased

(10)